Thanks for the replies. I did find that if I dialed back the preview quality enough, I was able to play without skipping any frames. I had Vista on my machine (an HP), but I hated it so much that I installed XP. I did order more RAM this morning. Currently, it has only 3 gb of RAM.
Maybe I should post on a different topic, but would like to know for the Canon (or I suppose, any AVCHD camcorder) what the best settings are for rendering for: (i) computer playback; (ii) Blu-Ray; and (iii) online HD, such as Vimeo and YouTube HD. Thanks.